The present invention relates to a checker head with a pin to be brought into electrical contact with an inspected object such as a printed circuit in order to inspect the characteristics. More in detail, the present invention relates to a checker head used with connecting to a circuit tester in order to conduct electricity between a circuit tester such as the DC circuit tester and a test pad established in an inspected object.
An example of conventional checker head is shown in FIG. 5. The checker head 70 shown in FIG. 5 is made of the large number of set of a first contact pin 81, a second contact pin 82, a spring 83 and a wired socket 84 being disposed linearly and inserted through six laminated Bakelite board 71-76. Still, the first contact pin 81 has the nail shape, and its tip protrudes from the Bakelite board 71 of the front.
Of course, through holes for the first contact pin 81 and the like to pass through each Bakelite board 71-76 are established. And, the through hole of the Bakelite board 71 has a small diameter in comparison with the through hole of the Bakelite board 72, so the projection of the first contact pin 81 would be controlled by the contact of the ring division of the first contact pin 81 at this level difference.
The spring 83 is disposed in compressed condition, and pushes the second contact pin 82 toward an upward direction in FIG. 5 and pushes the wired socket 84 toward a downward direction in FIG. 5. This push pressure makes electrical connection between the wired socket 84 and the first contact pin 81. Especially, when the tip of the first contact pin 81 is pressed to a test pad 98 of a printed circuit 96 which is an inspected object, the spring 83 is further compressed. The push pressure increases as the compression of the spring 83 increases, and thus the electrical connection becomes more certain.
Still, the wired socket 84 has a structure in which a wire division 84b is tightened in a cylindric socket division 84a and connected to a circuit tester.
However, this conventional checker head 70 is not applicable to the recent printed circuit whose size has been reduced. Since the sizes of the recent printed circuits have been reduced, there have been demands that sizes and intervals of test pads 98 are smaller. In order to respond to theses demands, the pitch (it is shown by xe2x80x9cpxe2x80x9d in FIG. 5) of the first contact pin of the checker head must be decreased.
However, the limitation to reduce the pitch p was 0.6 mm in the checker head 70 shown in FIG. 5, since the wired socket 84 is used. The wired socket 84 has the above-mentioned structure in which a wire 84b is tightened in the cylindric socket 84a. In order to reduce the pitch p, it is necessary to decrease the diameter of the socket. But, it becomes more difficult to introduce and fix the wire 84b in the cylindric socket 84a as the socket diameter decreases. After all, the socket with a large diameter has been used because it is easy to introduce and fix the wire 84b in the cylindric socket 84a. 
One means for solving the problems has been disclosed by Unexamined Japanese Patent Application Publication No. Hei. 6-148236 (corresponding to U.S. Pat. No. 5,410,260). In this publication, an invention in which elimination of a wired socket may reduce the pitch of pins has been disclosed. The composition of the invention is a checker head comprising a middle insulator having a support hole that supports a large diameter division of a pin in the shaft line direction and receives a coiled spring, and being united in a
To solve the problems, the first invention is a checker head comprising a pin to be brought into contact with a test pad of an inspected object, a leading wire being connected to a circuit tester, a spring being linearly provided between the pin and leading wire to contact both of the pin and leading wire, and a laminated body through which the pin, leading wire, and spring pass. And, the composition that the spring is always compressed can be added in this checker head.
This first invention""s specific example will be able to express as following. In a checker head comprising a front board having a hole, an electroconductive pin in which the tip division protrudes from the hole of the front board and is in contact with an inspected object, a checker head comprising a large diameter division which is disposed at the position in the rear from the front board and in contact with the marginal of the hole of the front board from the back surface side, a rear board which locates in the rear from the large diameter division and through which a leading wire passes, an electroconductive spring which is located between the large diameter division and the rear board, and the pin and the leading wire being electrically conducted through the spring in at least the condition that the pin is pushed to the rear board.
In this checker head, the large diameter division of the pin is located between the front board and the rear board. Moreover, the preceding end of the large diameter division is in contact with the marginal of the hole of the front board from the back surface side. Therefore, it is prevented that the pin is pulled out to front side of the front board. And, the spring is disposed between the large diameter division of the pin and the rear board, so the pin is pushed back by the elastic force when the pin is in contact with an inspected object and is pushed in. By this, the tip division of the pin and the inspected object surely contact and electrically conduct. And, the pin and the leading wire also contact through a spring each other and are electrically connected. In this case, the spring and the leading wire may be integratedly molded or may be united by joining different member together by welding or soldering, etc.
In addition, the specific example of the first invention can be added the structures in which a middle board is established between the front board and the rear board and has a large hole in comparison with the diameter of the large diameter division and the spring, and the large diameter division and the spring are located in the hole of the middle board. In this checker head, the spring and the large diameter division of the pin are together located in the hole of the middle board, so the hole positions the direction of the spring and the large diameter division in the plate surface of the front board and the like and their actuations are sure.
To solve the problems, the second invention is a checker head comprising a pin to be brought into contact with a test pad of an inspected object, a middle pin being in contact with the pin, a leading wire being in contact with the middle pin and being connected to a circuit tester, and the pin, middle pin, and leading wire being linearly disposed and passing through a laminated body including an elastic layer, and the elastic layer restricting their positions.
In addition, to solve the problems, the third invention is a checker head comprising a pin to be brought into contact with a test pad of an inspected object, a leading wire being in contact with the pin and connected to a circuit tester, and the pin and leading wire being linearly disposed and passing through a laminated body including an elastic layer, the elastic layer restricting their positions.
These second and the third invention""s specific example can be expressed as in a checker head comprising a front board having a hole, an electroconductive pin of which a tip division protrudes from the hole of the front board and is in contact with an inspected object, a checker head comprising a large diameter division being disposed in the rear position from the front board in the pin and being in contact with the marginal of the hole of the front board from the back surface side, and an elastic layer retaining the pin with adherence to the position in the rear from front edge of the large diameter division of the pin.
In this checker head, when the pin is in contact with an inspected object and is pushed in, the pin will be pushed back by the repulsion of the elastic layer which retains the pin with the adherence to the position in the rear from front edge of the large diameter division of the pin. By this, the tip division of the pin and the inspected object surely contact each other and electrically conduct. Thereupon, the tip division and the large diameter division of the pin may be integratedly mold or may be united by joining different member together by welding or soldering, etc. And, the position of the pin being adhered to and retained by the elastic layer is a part (except for the front edge) of the large diameter division or more rear part of the large diameter division.
Especially, the specific example of the second invention can be expressed as in a checker head comprising a front board having a hole, a pin of which a tip division protrudes from the hole of the front board and is contact with an inspected object, a checker head comprising a large diameter division being disposed in the rear position from the front board in the pin and being in contact with the marginal of the hole of the front board from the back surface side, a middle pin being disposed rear of the large diameter division, and an elastic layer retaining the middle pin with adherence to the middle pin.
In this checker head, the elastic layer adheres and retains the middle pin of the different body to the pin. Even if the pin and the middle pin are different bodies, when the pin is contact with the inspected object and is pushed in, the pin is pushed back by the repulsion of an elastic layer. Therefore, the tip division of the pin and the inspected object, and the pin and the middle pin surely contact each other and are electrically connected.
In addition, the specific example of the second or third invention can add the structure in which a middle board is established between the front board and the elastic layer and has a large hole in comparison with the diameter of the large diameter division, and the large diameter division is located in the hole of the middle board.
In this checker head, the middle board is established between the front board and the elastic layer, and they are laminated and made into a one-body. And, the hole of the middle board positions the large diameter division in the in-plane direction.